Google illustrates the single pane/multi-pane approach of condensing pop out selections into screen transitions when switching from tablet to smart phone. (Source: Google)

The action bar will now be on smart phones in pint size form, so beware. (Source: Google)

Android devs are urged to make their tablets apps friendly for small screens

Google Inc. (GOOG) is giving developers their first of the next version of Android, Ice Cream Sandwich. Ice Cream Sandwich will merge together the tablet and smartphone branches of Android. This is a drastic departure from the current situation where Android tablets are powered by the closed-source Android 3.0 "Honeycomb" (latest version 3.2), while smartphones are powered by a separate open source, Android 2.3.x "Gingerbread".

Ice Cream Sandwich is set to release in October or November 2011, according to Google's Eric Schmidt. When that release occurs, Google will become only the second major smartphone and tablet maker to use a single source to support both tablets and smart phones.

That creates both a unique opportunity and a unique challenge for developers of Android, the world's most used smartphone and second most used tablet operating system.
Android Developers Blog carried a special post entitled "Preparing for Handsets." The post is written by Scott Main, lead technical writer for Android's developer site. It offers a useful guide of how developers can minimize the pain of the multi-size transition. His guide offers suggestions for streamlining the "Action Bar" tablet-centric interface element, which will now appear in pint-size form on smartphone apps. The post also suggests that secondary menus now be placed alongside the main screen, for tablet devices, but use a screen transition in smartphones (a single pane/multi-pane approach).

The alternative to making a fully compatible app is to use techniques to prevent your tablet app from being installed on smart phones/small slabs. Android 3.1 and older apps bin screen sizes into four general classes and allow apps' xml code to define which sizes are supported via the "supports-screens" attribute. In Android 3.2, the latest version of Honeycomb, the "support-screens" entry sticks around, but its format changes. Now instead of bins, users define a specific minimum size they wish to allow. Setting this high enough will essentially disallow most smartphones.

An example of the code to ban smartphones in both 3.1 and 3.2 (and forward compatible with 3.x Ice Cream Sandwich) is:

Canadian smartphone maker Research in Motion, Ltd. (TSE:RIM) may soon follow Google's example and offer a homogenized OS for its tablets and smartphones. Currently, the company's PlayBook tablet runs on QNX, an OS RIM recently required. RIM is porting the OS for use in its BlackBerry business-minded smart phones. It plans to switch to QNX for its new smartphones in 2012.

Apple Inc. (AAPL), who sits in second place in the smartphone market, and first place in the tablet business, was the first vendor to offer a single operating system for both its tablet and its phone. Thus far this approach has appeared to overall be beneficial to developers. Like Ice Cream Sandwich, iOS reserves certain functions for tablets, but have large overarching similarities between tablet and smartphone code within its SDK.